Modern HVAC systems operate by circulating a refrigerant through a system in which heat is transferred between the conditioned space and the refrigerant. As seen in FIG. 1, the HVAC system includes a compressor, a heat exchanger (condenser), turbine/expansion valve, and through a heat exchanger (evaporator). During operation the refrigerant cycles through various components of the HVAC system changing phase and, consequently, undergoing a temperature change. As the refrigerant flows through the compressor, the refrigerant is typically compressed from a two phase liquid vapor mixture into a saturated vapor. The compression of the refrigerant increases the temperature and pressure of the refrigerant. As the refrigerant passes from the compressor to the condenser, it flows through the condenser coils allowing heat transfer to the ambient air which is passed through the coils by a condenser fan. Due to the heat transfer, the refrigerant changes phase from a saturated vapor to a saturated liquid. The refrigerant then flows through a turbine or expansion valve expanding adiabatically, decreasing the temperature and also the pressure. The cooled refrigerant then flows through the coils of a heat evaporator where heat is transferred from air blown through the evaporator by an evaporator blower. The cooled air is then circulated throughout the conditioned space. As the refrigerant passes through the evaporator, it undergoes a phase change from a liquid to a vapor as a result of the heat transfer from the directed air into the refrigerant.
HVAC systems utilized in commercial or large scale industrial settings utilize heat exchanges (condensers and evaporators) having high density coil matrixes having a thickness of 8 to 12 inches. The high density coil matrixes often include a plurality of heat exchanging coils extending 10 to 12 feet perpendicular to the air flow and stacked 10 to 12 feet in height. In order to provide adequate heat transfer between the coils and the air, each adjacent row of coils is offset allowing greater distance between each of the coils.
The heat exchanging coils are extremely susceptible to becoming fouled and compacted with a variety of airborne contaminants. As these coils become increasingly congested with airborne particulate, biological growth, and other debris, air flow through the coils becomes compromised. Further, the contaminants act as an insulation on the coil surface which prohibits the transfer of heat from the coil surface to the air in the condenser or the transfer of heat from the air to the coil surface in the evaporator.
The previously known coil matrix techniques have utilized caustic chemicals in conjunction with a high pressure power washer. However, the caustic chemicals corrode the coil matrix causing etching and pitting on the coil surface thereby degrading thermal performance. The corrosion of the coil surface often causes the coils to foul at an accelerated rate thereby aggravating the problem.
In addition, the previously known power washing techniques merely provide a cosmetic cleaning of the visible surface of the coil matrix as the application of high pressure water at an angle perpendicular to the coil surface cannot effectively clean beyond the outer coils due to the offset positioning of the adjacent rows of coils. The previously known coil matrix cleaning techniques are highly disadvantageous as the majority of the inner coils are not thoroughly cleaned. Further, the cosmetic cleaning of the visible surface of the coil matrix gives the appearance of a thoroughly cleaned coil matrix to both a technician and consumer who often attribute the decrease in efficiency in the HVAC system to other factors as the matrix coil appears to be contaminant free.
Thus there exists a need for a cleaning method for a heat exchanger of an HVAC system which thoroughly cleans the entire coil matrix by penetrating beyond the outer layer of visible coils and into the inner majority of the coil matrix. Further, there exists a need for a method and system to verify the effectiveness of cleaning the coil matrix and to provide both the technician and consumer evidence in the form of the changing operating efficiency before and after the cleaning process.